Spring winder



March 17, 1953 R w, PALMER 2,631,639

SPRING WINDER Filed June 13. 1947 wmf Patented Mar. 17, 1953 UNITED STATES PATENT SPRING WINDER Richard W. Palmer, Whittier, Calif.

Application June 13, 1947, Serial No. 754,335

4 Claims. (Cl. 153-65) My invention relates in general to apparatus for forming wire, or the like, into coils and, more particularly, to an apparatus for forming spring Wire into coil springs.

A primary object of the invention is to provide an apparatus for forming a pre-tensioned spring, i. e., a spring which is in tension when undeflected and which thus `tends to shrink upon itself. Another object is to provide such a pre-tensioned spring.

Coil springs of this character may be formed by twistingY the spring wire to an extent sufiicient to produce a permanent set therein as the wire is coiled, an important object of my invention being to provide an apparatus which includes a simple `and improved means for twisting the wire as it is fed to a coil forming means.

Another object of the invention is to provide a wire forming apparatus wherein the coil forming means is rotatable and wherein the wire is fed to the coil forming means along a path such that the rotation ofA the coil forming means results in twisting of the wire to the desired extent. More specically, it is an object of the invention to provide an apparatus wherein the wire tobe coiled moves along a path which extends in the direction of the axis of rotation of the coil forming means so that the lcoil forming means rotates the wire about the longitudinal axis of the wire as it rotates. A further object is to provide a restraining means for preventing such rotation of the wire about its own axis at a point spaced from the coil forming means so that the wire is twisted intermediate the restraining means and the coil forming means. Y

Still another object of the invention is to provide an apparatus of the foregoing general character wherein the coil forming means includes a rotatable arbor and includes means carried by the arbor for coiling the wire around a mandrel. A related object is to provide means Vcarried by the arbor for rotating the wire about its own longitudinal axis as it is fed to the coiling means, the aforementioned restraining means cooperating with the wire rotating means toA twist the wire.

An object in connection with one embodiment of the invention is to provide a coil forming means which comprises amandrel whose longitudinal axis substantially coincides with the axis of rotation of the arbor, and which comprises means carried vby the arbor for guiding the wire along apath having a first portion which is substantially perpendicular to the axis of rotation of the arbor i and which leadsrto the mandrel, and having a Y *second portion which'substantially coincideswith`1 the axis of rotationv of the arbor, whereby the -coil forming means rotates the wire about its own longitudinal axis when the arbor is rotating and cooperates with the restraining means to twist the wire.

In another embodiment of the invention it is an object to provide a coil forming means wherein the mandrel around which the wire is wound by the aforesaid coiling means on the arboris perpendicular to the axis of rotation of the arbor so-that the mandrel serves as a wire rotating means which cooperates with the restraining means to twist the wire fed to the coiling means.

A further object of the invention is to provide an apparatus for forming a continuous coil spring which mayV be severed into suitable lengths.

An important object is to provide a spring Winder which is capable of twisting the wire to be coiled to such an extent that the resulting spring has a load-deflection curve which intersects thezero tension axis at a negative length. More specically, it is an object to provide a spring winding apparatus which is capable of twisting the wire to such an extent that the tension'in the resulting spring, when undeflected, approaches the maximum tension therein when the spring is fully deflected. An important 0bject of the invention is to provide such a spring.

The foregoing objects of myinvention and the advantages Vsuggested thereby, together with various other objects and advantages which will be evident hereinafter, may be attained through the employment of the exemplary embodiments illustrated in the accompanying drawing and described in detail hereinafter.

Referring to the drawing:

Fig. 1 is a semi-diagrammatic view showing a wire formingapparatus which embodies the fun damental principles of my invention;

Fig. 2 is a perspective view showing a coil forming means which forms part of the apparatus;

Fig. 3 is a perspective view of a mandrel formng part of the coil forming means shown in Fig. 4 is an elevational view showing a coiling means, or coiling head, and mandrel which form part of the coil forming means shown in Fig. 2;

Figs. 5 and 6 are views illustrating the operation of the coiling head and mandrel;

Fig. 7 is a plan view of another embodiment of a springl winding apparatus which includes'v means vIt -for feeding wire- I6 froma suitable source (not shown) to rotatable means, indicated generally by the numeral I1, for forming the wire into a continuous coil I 8 which may be severed periodically to provide coil springs of the desired lengths, as by a cutting mechanism indicated generally at I9, for example. The coil forming means I1 is rotatable relative to supporting structure indicated generally by the numeral 20 about an axis A-A, and the wire I6 is fed to the coil forming means along a path 2l which extends generally in the direction of the axis A-A so that the coil forming means rotates the wire about the longitudinal axis of the wire. Such rotation of the wire I6 by the coil forming means I1 is prevented at a point 22 spaced from the coil forming means by restraining means 23 so that the, wire is twisted throughout that portion thereof which lies between the coil forming means and the restraining means. Such twisting Aof the wire fed to the coil forming means results in a pre-tensioned ,coil I8 which tends to shrink upon itself in the manner previously discussed herein, provided, of course, that the direction of rotation of the coil forming means is as indicated by the arrows 24 inthe drawing. It will be apparent that if the directionrof rotation is reversed, the resulting coil will not be pre-tensioned, but will tend to kextend or Vstraighten itself.

.Considering my spring winding apparatus in more detail, in the particular construction shown in the drawing the feeding means I is adapted to push the wire I6 through the coil forming means I1, although it will be understood that I may employ a feeding means which is adapted topull the wire through the coil forming means as will be pointed out in more detail hereinafter. Also, in the particular construction illustrated the restraining means 23 forms part of the feeding means I5, i. e., the feeding means performs the function of the restraining means,

lalthough a separate restraining means may be employed if desired.

The feeding means I5 includes a pair of counter-rotating rollers 26 and 21 which receive the wire I6 therebetween and which push it through the coil forming means I1, the spacing between the rollers being such that the rotation of the `wire I6 which is caused by the coil forming meansY I1 is prevented at the point 22 so that such rotation is not carried back to the p source of the wire. Thus, in addition to serving as the feeding means, the rollers 26 and 21 serve as the restraining means 23 so as to produce a twist in the wire fed to the coil forming means. If desired, an additional pair of counterrotating rollers 28 and 29 may be employed forV feeding the wire IS through the coil forming means I1 and for further preventing twisting of the wire back to the source.

Although any suitable means for driving the rollers 26 to 29 may be employed, I have shown a construction wherein these rollers are all driven by a common gear 32 which is meshed with gears 33 and '34 on the rollers 21 and 29, respectively, the gear 33 being meshed with a gear 35 on the roller 26 and the gear 34 being meshed with a gear .36 on the rollerV 23. Connected to the common drive gear 32 is a bevel gear 31 which is meshed with a pinion 33, the latter.v being driven by a pulley 39 through the medium of a shaft 40. The pulley 39 is driven :v a pulley 4I through a belt 42, the pulley il ng mounted on a countershaft 43 whichis drive -..en by av motor 44 through the medium of;

a belt trained over pulleys 46 and 41 mounted on the countershaft and on the shaft of the motor, respectively.

The coil forming means I1 includes an arbor 55 which is supported by bearings 5I carried by the supporting structure 20 as shown in Fig. 1. The arbor carries die means 52 for coiling the wire I6 around a mandrel 53, and carries means 54 for guiding the wire to the coiling means along the path 2| so that rotation of the arbor results in twisting of the `wire throughout that portion of its length which lies between the coiling or die means 52 and the restraining means 23. As best shown in Figs. 1 and 2, the guiding means 54 may include a pair of plates 55 which are mounted on a ilat portion 56 of the arbor 56 and which are connected to the arbor by bolts 51, the plates 55 being provided lwith complementary grooves 55a therein which form part of the guide path 2l. The arbor 55 is provided vwith an opening 5B on the axis of'rotation A--A of the arbor through which the wire I3v may be fed into the grooves 55a in the plates 55. As best shown in Fig. l, the grooves 55a provide the guide path 2I` with a portion 6I which is substantially perpendicular to the axis of rotation A-A of the arbor and which leads to the coiling means 52, and provide the guide path with a portion 62 which substantially coincides with the axis of rotation A-A, the portions 6I and 52 of the guide path being connected by a curved or looped portion 63 which is spaced from the axis of rotation of the arbor.

It will be apparent that-causing the wire I6 to follow the guide path 2| in this manner will result in rotation of the wire about its own longitudinal axis as the arbor 50r rotates, such rotation of the wire being prevented back of the point 22 by the restraining means 23. Thus, that portion of the wire I6 lying between the restraining means 23 and the coiling means 52 isV twisted so that the coiling means produces a pre-tensioned coil I8 as -will be discussed in more detail hereinafter. To insure that the twist produced in the wire I6 in this manner will be distributed substantially uniformly, the grooves a in the plates 55 forming the guiding means preferably provide a guide passage which is a little larger than the wire so that the wire may rotate freely therein.

As previously mentioned, the twisted wire fed to'the coiling means 52 is wound around the mandrel 53 to form the continuous coil I8. In general, the coiling means 52 includes a coiling member 55 which is attached to a supporting arm 65 byl bolts 31, the supporting arm being mounted on the flattened portion 53 of the arbor in a rigid manner by a bolt 58. The mandrel 53 is provided with an enlarged shank'g which is disposed in an axial bore 15 in the arbor 50 and is rigidly connected to the arbor by the bolt 66, which bolt extends through an opening 1I in the shank of the mandrel.

Considering the structure of the coiling means 52 in more detail, the shoulder 12 formed by the enlarged shank 59 of the mandrel 53 has the form of one turn of aY helix, the portion 6I wirev I3 engages a curved portion 13 of the coiling 'member 65 which bends the wire and coils. it around the mandrel 53 as best shown in Figs. 5 and 6, .the direction of motion'impartedito the trained over pulleys 83 and Iwire by the feeding means l5 being indicatedY As best shown in Fig. 4, the the coiling member B conby the arrowsV 14. vcurved portion 13 of verges in the direction of movement of the coil is relieved somewhat, as indicated at 11, to allow for spring back of the convolutions of the coil as they move axially along the mandrel.

It will thus be apparent that as the wire I6 is fed through the coiling means 52 by the feeding means I5, the helical shoulder 12 on the mandrel 53 and the curved portion 13 of the coiling member 65 cooperate to coil the wire I6 around the mandrel to produce the continuous helical coil I8 which may be severed periodically into springs of suitable lengths by the cutting mechanism i9. It will also be apparent that the coiling means 52 will operate to produce the coil I8 even though the arbor 5|) is not rotated, but such a coil will not be pre-tensioned whereas pre-tensioning of the coil I8 does occur when the wire I6 fed to the coiling means 52 is twisted in the manner previously described by rotating the arbor 59 in the direction indicated by the arrows 24 throughout the drawing.

In the particular construction illustrated in the drawing, the arbor 50 is driven fromv the countershaft 43 through a variable speed mechanism 18 to permit varying the amount of twist Vproduced in the wire IB fed to the coiling means 52 so as to Vary the amount of pre-tensioning of the coil I8. The variable speed mechanism is driven by the countershaft 43 through the medium of a belt 19 trained over pulleys 80 and 8|, and the variable speed mechanism drives the arbor 50 through the medium of a belt 82 Although the spring winding apparatus thus far described includes the feeding means I5 for pushing the wire I6 through the coil forming means I1, a feeding means (not shown) which acts on the completed coil I8 to pull the wire through the coil forming means may be employed if desired. With such a pull type feeding means the rollers 25 to 29 would serve merely as the restraining means 23 for preventing twisting of the wire back to the source. In all 'other respects, the operation of the spring Winding apparatus incorporating a pull type feeding means `is identical to that of the apparatus with the push type feeding means I5.

In Fig. '1 of the drawing, I show a coil forming means 9U whose operation is somewhat different from that of the coil forming means I1 which was describedpreviously. The coil'forming means 9E! includes an arbor 9| which is substantially identical to the arbor 50 and which is interchangeable therewith. The arbor 9| carries a mandrel 92 which is substantially identical to the mandrel 53 except that it is attached to the arbor with its axis perpendicular to the axis of rotation A-A instead of being attached thereto with its axis coinciding with the axis of rotation. The mandrel 92 may, for example, be threaded into an opening in the arbor 9| as indicated in Fig. 7.

A coiling member 93, which is substantially identical to the coiling member 65 described previously, is mounted on a flattened portion 94 of the arbor 9| in a position such that the coiling member lies substantially on the axis of rota- 6 tion A-A of the arbor, the coiling'member being attached to the arbor by bolts 95, for example. In the coil forming means 99 shown in Fig. '1, the wire is fed through an axial openingl 96 in the arbor 9| and is coiled around the mandrel 92 by the coiling member 93 in a manner similar to that previously discussed. However, since the axis of the mandrel 92 is perpendicular to the axis of rotation A-A of the arbor 9|, the resulting coil I8 comes off the mandrel at right angles to the axis of rotation of the arbor instead of along the axis of rotation. In order to return the coil I8 to the axis of rotation of the arbor 9|, I provide a curved guide 91 which conducts the coil to an axial opening 98 in the arbor. The coil I8 emerging from the axial opening 98 may be severed into suitable lengths by the cutting mechanism I9, for example.

It will be noted that if the arbor 9| is rotated about the axis A-A in a manner similar to that previously described, the mandrel 92 rotates the wire I 6 about its longitudinal axis, such rotation of the wire being prevented by the restraining means 23 in the manner previously described so as to twist the wire as it is coiled around the mandrel 92. Thus, the coil I8 formed by the coil forming means 9D is pre-tensioned due to the twisting of the wire as it is formed into the coil. v

Referring to Fig. 8, the straight line represents the load-deflection curve for a typical coil spring produced with either the coil forming means I1 or the coil forming means 90, the abscissa in the diagram being the length ofthe spring and the ordinate being the tension in the spring. In other words, the line |09 represents the tension in the spring expressed as a function of the degree of deflection (extension) of the spring. It will be noted that if the load-deflection curve |90 is extended as indicated by the dotted portion IUI thereof until it intersects the zero tension axis of the diagram, it intersects this axis at a point indicating a negative length. The load-deflection curve |00 for a spring produced by my invention may be expressed by the equation t=lc (Z-c) wherein t is the tension in the spring, 7c is its spring constant, Z is the length of the spring, and c is a negative constant repre- 'sentingr the length which the spring would have -will be noted that this curve intersects the zero tension axis at a positive value of the length of the spring. Thus, in effect, pre-tensioning a spring in the manner described herein shifts its load-deflecting curve so that the spring operates on a, higher portion of the curve for the same deection. In other words, the apparatus disclosed herein is capable of producing a spring which, when undelected, provides a spring force equal to that provided by a normal spring of comparable size when partially or fully extended, depending on the extent to which the wire is twisted in forming my pre-tensioned spring.

Such pre-tensioned springs may be used in any installation where large spring forces must be attained with limited deflection.

I have found, for example, that the apparatus disclosed herein may be used to produce a spring which, when undeflected, provides a spring 'force :assunsel in excess of 75%-` of that attainable therewith when fully extended; However, the degree of pre-tensioning may be varied as desired by varying the extent to which the wire I6 is twisted in coiling it, i. e., by varying the speed of rotation of the coil forming means i1 or 90 with respect tothe rate of feed of the wire. For example, 100% of the maximum spring force which a spring is capable of providing may be pre-tensioned in it by increasing the speed of rotation of the coil forming means with respect to the rate of feed of the wire to a suilicient extent, the only limit to the degree of pre-tensioning being the torsional stress limit of the wire.

Although I have disclosed exemplary embodiments of invention herein for illustrative purposes, it will be understood that I do not intend to be limited thereto since various changes, modifications and substitutions may be incorporated in such embodiments without departing from the spirit of the invention, and I hereby reserve the right to all such changes, modifications and substitutions as properly come Within the scope of the invention as set forth in my appended claims.

I claim as my invention:

1. In a wire forming apparatus, the `combination of: a supporting structure; an arbor carried by and rotatable relative to said supporting structure; a mandrel having a longitudinal axis which vcoincides with the axis of rotation of said arbor, 'said mandrel being carried by said arbor and being rotatable therewith; coiling means carried by said arbor so as to be rotatable therewith for coiling the wire around said mandrel and having a helical shoulder to advance the resulting coil along said mandrel; guide means carried by said arbor so as to be rotatable therewith and providing a continuous guide path having a rst portion Which is generally perpendicular to the axis of rotation of said arbor and which leads to said coiling means, and having a second portion which is spaced from said coiling means and which extends in the direction of the axis of rotationof said arbor, whereby, when said arbor is rotated, the wire fed to said coiling means is rotated about the longitudinal axis of the wire; feeding and restraining means for feeding the wire to said coiling means and for preventing rotation of the wire about its longitudinal axis at a point spaced from said coiling means so as tol twist the wire intermediate said feeding and restraining means and said coiling means; and means for rotating said arbor, thereby also rotating said mandrel, said coiling means and said guide means.

2. A wire forming apparatus as set forth in claim l wherein said second portion of said guide path substantially coincides with the axis of rotation of said arbor.

3. In a wire forming apparatus, the combination of: a supporting structure; an arbor carried. by androtatablerelative tov said supporting structure.; a mandrel? carried by said arbor so as to be rotatable therewith and having a longitudinaly axis` which is substantially perpendicular to the axis of rotation of said arbor;y coiling means carriedby said arbor so as to be rotatable therewith for coiling the wire around said mandrel and having a helical shoulder to advance the. resulting coil along said mandrel; means on said arbor so as to be rotatable therewith for guiding the wire fed to said coiling means alongva path which, at least in part, extends generally parallel to the axis of rotation of said arbor, whereby said mandrel rotates the wire fed to said coiling means about the longitudinal axis of the, wire, when said arbor is rotated; means for rotating said arbor, thereby also rotating said. mandrel,y said. coiling means and said guiding means; and feeding and restraining means for feeding the wire to said coiling means and for preventing rotation of the wirel fed to said coiling means about its longitudinal axis at a point spaced from said coiling means so as to twist the wire intermediate said feeding `and restraining means and said coiling means.

4. A. wire forming apparatus as set forth in claim 3 wherein said path of the Wire fed to said coiling means substantially coincides with the axis of rotation of said arbor.

RICHARD W. PALMER.

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